Centrerless grinding machine



Aug. 6, 1940. .1.E. BERGSTFRM I CENTERLESS GINDING' MACHINE Filed Aug. 4.. 1937 INVENTOR; JOHAN ERIK BERGTRQ` -BYZ 9 ATTdRNa/s Patented Aug. 6,, 1940 v I UNITED vsfm'rlas I 2,21o,131 g CENTERLESS GrItINDlNGrv MACHINE Johan Erik Bergstrm, Halmstad, 'Sweden Application August 4,

1937, Serial NO. 157,273

In Sweden August 17, 1936 1 Glaim.

The presentl invention relates to centreless grinding machines of the kind in Which the Work is fed forwards during the grinding Operation between a grinding Wheel rotatable about a horizontal axis, and a rotatable regulating Wheel, the axis of Which is adjustably inclined With relation to the axis of the grinding Wheel for regulating the Work feed and is more particularly concerned With machines in Which the grinding separate motors and in which the motor of the regulating Wheel, the regulating Wheel itself and the interconnecting gearing are mounted on a pivotal Supporting plate, frame or the like.

The invention relates more particularly to improvements in driving means for the regulating Wheel Where the latter is geared to the driving motor by means of a worm gear drive, the essential object in view being to develop an arrangement that facilitates thelmounting of the driving means for the regulating Wheel and at the same time allows the elimination of any-excessive play between the worm and. .the worm Wheel and makes possible subsequent afdjustments of the worm in relation to the` WormWheel to take up Wear of said members so that no lost motion will occur between the said members, which is of great importance for obtaining a Well-ground product of superior accuracy. Y

The arrangement according to the invention resides in journalling the motor-driven shaft on Which the driving Worm is secured, in a bushing or the like Which is pivotally mounted about an axial line which is eccentric in relation to the motor-driven shaft so that by turning said bushing about said axis lthe distance between the motor-driven shaft and the shaft of xtheWorm Wheel onWhich the regulating Wheel is mounted may be adjusted at Will. i.

According to a further feature ofthe invention, When the shaft of the regulating Wheel is journalled in a conical bearing, the above referred to eccentric journalling of the xbushing is so arranged vvith relation to -the motor shaft that, When turning the bushing toeliminate lost motion between the worm and the Worm Wheel, the worm. Will exert a pressure upon the worm Wheel Which is so directed that it tends to move the shaft of the regulating Wheel in a direction such that the journalling of the latter shaft in the conical bearing Will be maintained free from play.

A constructional embodiment of the invention will now be described by Way of example With. reference to the accompanying drawing in Which:

Wheel and the regulating Wheel are driven by` Fig. 1 is a plan vieW,,partly in horizontal section, of a centrelessgrinding machine according to the invention, while Fig. 2 is a Vertical section along the line II-II in Fig. 1, and i Fig. 3 is-a longitudinal section along the line III-III in Fig. 2, the eccentric arrangement of the screws in each of these figures being shown 7somewhat exaggerated for the sake of clarity.

Referring first to Fig. 1, reference numeral l 10 designat-esthe regulating Wheel and Zthe grind- .ing Wheel, between Which the Work 4, while resting on the Work-rest slide 3, is fed forwards in known manner by giving the regulating Wheel an axially inclined position in relation to the grindl15 ing Wheel. The regulating Wheel l and its driving motor 9 are both mounted on the same supporting frame or plate 6. 39 denotes a slide displaceable along the main machine frame. The Supporting frame or plate 6 together With the l.20 motor 9, the regulating Wheel and driving mechanism for the latter are pivotally mounted asa Whole on the slide 39 about a horizontal pivot shaft 'l so that the regulating Wheel Will be pivotable in a Vertical plane parallel With the direc- `.25 tion of feed of the Work and may be adjusted to occupy different inclined positions vvith .relation thereto. The rockng of the frame B about the shaft l may be effected by means of a screw 40 threaded into the slide 39 and having its end k abutting against a pin 4l secured to the frame or plate G. The latter plate may be looked to the slide 39 after adjustment by means of bolts 42.

The. regulating Wheel l is secured to the shaft 5 suitably journalled in the frame or plate 6. k: The regulating Wheel and' the shaft 5 are so arrang-ed that the horizontal pivot shaft 'I is situated in the central plane of the regulating Wheel perpendicular to its axis 5 and, if extended, Will intersect the said axis at right angles. The point um of intersection vvill thus ble the exact centre of the regulating Wheel and it Will be readily understood that when the frame 6 is turned about the pivot shaft 1 to different positions, the centre of the regulating Wheel Will always be maintained in an unchanged position.

- A worm Wheel 8 is secured to the shaft 5 while the motor 9 is secured to the frame or plate B by means of a fiange Ill and screws ll. A motor shaft indicated generally at l2 carries a worm l3 in mesh With the worm Wheel 8. The motor shaft is made in two parts Ill and 15 Which are interconnected by means of a coupling that permits a vibrationless running while allowing the shaft parts l4 and l5 to lie eccentric to one another.

As shown the shaft portion 14 carrying the worm l3 is connected to the motor portion l5 of the shaft by means of a loose coupling member 3l which is provided on opposite sides with grooves 32 and projections 33 arranged at right angles to each other and Which engage complementary projections 34 and grooves 35 on the respective shaft portions IE and Ill. In the construction shown in the drawing, the projections 34 are provided on a sleeve 36 keyed to the shaft portion 15.

A further sleeve lt is secured to the shaft portion M which is journalled, as illustrated, in a bushing l9 by means of conical roller bearings 11 and 18. The bushing IS is mounted in the Supporting frame or plate 6 on two concentric cylindrical sliding surfaces 20 and 2l, Which are, however, eccentric With relation to the motor shaft 12. Reference numeral 22 (Fig. 2) designates the aXial line of the surfaces 20 and 2l,

being situated somewhat to one side of the motor shaft l2. The bushing l9 is provided With a flange 23 which is concentric With the motor shaft I2 and is secured between the fiange IO of the motor and the frame 6 by means of the screws H Which pass through elongated arcuate holes 25 (Fig. 2) in the flange 23. These holes 25 are curved concentrically about the axis 22 and are thus eccentrically arranged in the flange 23. The bushing [8 is also secured to a partition Wall 26 provided With the bearing surface 2l in the Supporting frame 6' by means of screws 21 passing through sirnilar elongated holes 28 lin the wall 24 of the bushing, said holes being also curved concentrically about the aXis 22.

When the Worm [3 is to be adjusted with relation to the worm` Wheel 8, the screws ll are first extracted, Whereupon the motor can be removed. The screws 21 are then loosened, whereupon the bushing IB may be turned due to the provision of the elongated holes 28. During this turning of the bushing the centre of the shaft portion l4 is moved along a circular path having the axis 22 as a centre and by bringing the shaft portion l4 towards the shaft 5, any play caused by Wear can be eliminated. The bushing is turned until it is felt by the hand that a suitable play between the Worm and the worm Wheel has been provided. In doing so, it is convenient to rock the sleeve IG, secured to the shaft portion l4, backwards and forwards by means of the nut 29 Which is secured to the sleeve IB by a locking screw (not shown). When the desired adjustment has been made, the screws 21 are tightened, the motor is re-fitted in its plate and the screws H tightened.

When turning the bushing l9 so that the lost motion between the Worm and the worm Wheel is eliminated, the Worm Will eXert a pressure upon the Worm Wheel 8 which tends to displace the shaft 5 of the regulating Wheel in an axial direction. When said shaft, as shown, is provided With a conical journal 31 running in a conical bearing 38, said axial pressure must not be in such a direction that it tends to create play between the journal 31 and the bearing 38, on the contrary it should have such a direction that it tends to move the shaft 5 in a direction to maintan the journalling of the shaft without play in the bearing 38, i. e. the pressure should be directed outwards in the direction of the arrow shown in Figs. l and 2. This action is obtained by so arranging the eccentric mounting of the bushing 19 With relation to the motor shaft that the motor shaft |2 When turned about the axis 22, as described above, is moved outwards in the direction of the arrow simultaneously With its being brought nearer to the shaft 5. According to Fig. 2 the axis 22 of the bushing 19 is located below and on the outer side of the shaft I2 relatively to the regulating Wheel. It is suitable to locate the axis 22 on a radial line through the axis [2 making an angle a With the horizontal plane equal to about 30.

An adjustment for the Wear in the conical roller bearings |1 and |8 may also be readily effected by loosening the locking screw (not shown) of the nut 29 and turning the latter until the desired amount of play in the bearings is restored.

The lubrication of the Worm is eifected by means of a dipping Wheel 30 running in a bath of lubricating oil in the bottom of the gear housing.

Having now particularly described the nature of my invention and the manner of its Operation what I claim is:

A centreless grinding machine, comprising a machine frame, a grinding Wheel, a rotatable regulating Wheel adapted to roll against a side of the work opposite to that of the grinding Wheel, the shaft of the regulating Wheel being arranged in a plane parallel to the shaft of the grinding Wheel, a Work-rest supporting the Work from below While being ground, driving means for the grinding Wheel, a separate electrical motor driving the regulating Wheel, a housing in Which the regulating Wheel and its driving motor both are mounted and their shafts journalled, said housing being pivotally mounted and adapted to adjust the axis of the regulating Wheel to inclined positions in relation to the axis of the grinding Wheel in a plane parallel with the direction of feed of the Work; a Worm` secured to the shaft of said driving motor in mesh with a Worm Wheel secured to the shaft of the regulating Wheel, the shaft of said driving -motor being journalled in a bushing pivotally mounted in said housing about an axial line, which is eccentric With relation to the motor shaft so that by turning said bushing about said axis the distance between the motor shaft and the shaft of the regulating Wheel may be adjusted to eliminate dead motion between the worm and the worm Wheel, said shaft of the regulating Wheel being journalled in a conical journal bearing, and the eccentric mounting of said bushing With relation to the motor shaft being so arranged that, when the bushing is turned to eliminate lost motion between the worm and the Worm Wheel, the worm will eXert a pressure upon the worm Wheel Which tends to move the shaft of the regulating Wheel in a direction such that the journalling of the latter shaft in its conical bearing vvill be maintained free from play.

JOHAN ERIK BERGSTRM. 

